On-line pollution leakage current monitoring system

Surface flashovers of high voltage insulators occasionally occur in areas where industrial or coastal pollution is present. Particularly they may take place on sites where the level of pollution has been underestimated at the design stage or the equipment and its insulation have not been properly designed for the specified level of pollution. Regressive change in the pollution environment of established sites due to increase in industrial or agricultural activities in the area may also lead to surface flashovers. Investigations of several external flashovers on 500 kV equipment on one site in the Victorian power system (Australia) revealed that the surface pollution was one of the contributing factors of such flashovers. Soon after these flashovers, a project with the aim to design and develop a simple and effective pollution monitoring system has commenced. Full description of the developed system, the results of its extensive laboratory testing, calculation of the pollution leakage currents for the different layer thickness and conductivity are reported in this paper